Touchscreens, which are ubiquitous components of smart phones and tablets are fast becoming ever more popular, if not necessary, user interfaces for a rapidly increasing selection of computing and communication devices as the touchscreens become less expensive to manufacture in ever larger sizes. Today they may be found by way of example, in a variety of sizes as interfaces for laptops, desktops, plant control systems, and are replacing whiteboards and large video screens as presentation displays in meeting and conference rooms.
As its name implies, a user interacts with a touchscreen by touching the screen with a fingertip or tip of a passive or active stylus. The touchscreen may sense a location of the fingertip or stylus tip on the touchscreen by inductively or capacitively coupling to the tip and transmit signals indicating the location to a computer coupled to the touchscreen. The computer may operate to associate the location of the tip with a location of a feature that the computer displays on the touchscreen to determine how to respond to the user.
A passive stylus mimics a finger and typically comprises an electrically conductive rod having a tip of a size similar to that of a fingertip. It does not actively transmit signals of its own or process signals generated by a touchscreen, and therefore does not need and does not comprise or have access to a power source. As a result, resolution of location of a passive stylus tip on a touchscreen is generally relatively coarse, and a passive stylus may be constrained by relatively coarse spatial interaction with a touchscreen. An active stylus on the other hand comprises or has access to its own power source and may be configured to transmit signals to a touchscreen as well as to receive and process signals from the touchscreen. The tip of an active stylus may be small in comparison to a fingertip and is typically locatable on a touchscreen with fine spatial resolution that enables fine line drawing and detail selection of features on the touchscreen that are not readily supported by passive stylus. In addition, an active stylus may offer advantageous functions such a pressure sensing that are generally not available from a passive stylus. The stylus typically comprises at least one state actuator manually operable by a user, for example by pressing on a button and/or moving a slider that the stylus comprises, to control stylus functions.